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Biology Year 13 > Neuronal Communication✅ > Flashcards

Neuronal Communication✅ Flashcards

1
Q

What pathway does a nervous response usually follow

A

Sensory receptor
Sensory neurone
Relay neurone
Motor neurone
Effector

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2
Q

What is the function of a sensory neurone

A

Transmits impulses from receptors to relay neurones in the central nervous system

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3
Q

What are the key structural features of a sensory neurone

A

One dendron (carrying impulse from receptor to cell body)

One axon (carrying impulse from cell body to a relay neurone)

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4
Q

What is the function of a relay neurone

A

Transmit impulses between neurones

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5
Q

What are the key structural features of a relay neurone

A

Many clusters of dendrites, each leading to a dendron.

Each dendron passes to central cell body

Short axon carries impulses from the cell body to many synaptic endings

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6
Q

What is the function of a motor neurone

A

Transmit impulses from a relay neurone to an effector (ie muscle or gland)

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7
Q

What are the key structural features of a motor neurone

A

Dendrites leading to the cell body. One long axon (carrying impulses from cell body to effector)

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8
Q

How do sensory and motor neurones look different

A

Sensory: cell body and nucleus in middle of dendron

Motor: cell body and nucleus left of dendron

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9
Q

What does a dendron, axon, dendrites, myelin sheath, nodes of ranvier, cell body and nucleus look like on a diagram of a neurone

A

Dendron: the start of the axon

Nucleus: small circle in cell body

Cell body: surrounds nucleus

Dendrites: little circles on end of

Myelin sheath: around the axon

Node of ranvier: gaps in myelin sheath

Axon: line connecting cell body away

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10
Q

What are myelin sheaths made from, what do they do

A

Fat produced by Schwann cells

Speed up nervous impulse by enabling saltatory conduction (axon membrane can depolarize only at nodes of ranvier, action potential jumps between nodes which is more efficient then entire membrane being depolarized

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11
Q

What do receptors do

A

Detect change in environment and convert stimulus into electrical impulse

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12
Q

What are the 5 types of stimulus

A

Pressure
Light
Chemicals
Temperature
Sound

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13
Q

What receptor and describe mechanistic detail for pressure stimulus

A

Receptor: pacinian corpuscle

Detail: pressure applied to skin opens stretch-mediated sodium ion channels, triggering an action potential

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14
Q

What receptor and describe mechanistic detail for light stimulus

A

Receptor: rods cells (in retina of eye)

Detail: light causes a chemical reaction to occur in rod cells (ie breakdown of rhodopsin), which alters the permeability of the cell membrane to sodium ions

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15
Q

What receptors and describe mechanistic detail for chemical stimulus

A

Receptors: taste receptor, olfactory cells

Detail: molecules or ions (eg salt, sugar, odour molecules) bind to receptors on the receptor cell membranes, this causes a second messenger response, cAMP levels rise and alter permeability of the cell membranes to Na+ ions. Depolarization occurs and triggers an action potential

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16
Q

What receptor and describe mechanistic detail for temperature stimulus

A

Receptor: thermoreceptors

Detail: specialized sensory neurones. The permeability of their membranes to Na+ ions changes with temperature

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17
Q

What receptor and describe mechanistic detail for sound stimulus

A

Receptor: hair cells (in the ear)

Detail: sound waves move cilia on hair cells, which triggers changes in membrane permeability to K+ ions

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18
Q

What is action potential

A

The change in potential difference across a neurone membrane following a stimulus (approx +40mV)

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19
Q

What is the resting potential in mV

A

-70mV

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20
Q

How does the sodium-potassium pump produce resting potential

A

3 Na+ ions pumped out of neurone (by active transport) for every 2 K+ ions pumped in. This sets up an imbalance of positive charge (ie outside the neurone is more positive then inside)

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21
Q

How do K+ channels produce resting potential

A

Some K+ channels remain open, this enables some K+ ions to diffuse out of neurone, down a concentration gradient. Even more positive charge therefore builds up outside of the neurone

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22
Q

What happens during an action potential

A

Resting potential

Na+ channels open. Na+ ions diffuse into neurone down an electrochemical gradient

Initial influx on Na+ ions causes more voltage gated Na+ channels to open (depolarization)

Na+ ions continue to diffuse into neurone through voltage gated Na+ channels until potential difference reaches +40mV. Voltage-gated Na+ channels then close and voltage-gated K+ channels open

K+ ions diffuse out of neurone, reducing the positive charge inside the neurone and repolarising the membrane

Voltage-gated K+ channels close. The membrane becomes hyper polarized (due to K+ ions leaving, inside becomes more negative then resting state). Known as refractory period- no more action potential occurs until resting potential restored. Na-K pumps return the neurone to resting potential

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23
Q

The propagation of an action potential involves what events

A

Na ions enter a neurone and depolarize it

Na ions diffuse further along the neurone

The increased positive charge caused by diffusion of Na ions open more voltage-gated sodium ion channels

Action potential passes along the neurone

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24
Q

What 3 factors affect the speed of nerve impulses

A

Greater axon diameter (reduced resistance to ion flow)

Higher temperature

Presence of myelin

25
Describe the transmission across a synapse
Action potential passes to end of presynaptic neurone (presynaptic knob) Voltage-gated Ca2+ ion channels open Ca2+ ion influx causes vesicles containing neurotransmitters (acetylcholine) to fuse with neurones cell membrane Neurotransmitters (acetylcholine) released into synaptic cleft by exocytosis Neurotransmitters (acetylcholine) diffuse across synaptic cleft and bind to receptors on postsynaptic neurones cell membrane Na ion channels and triggered to open, causing depolarization and an action potential in postsyanptic neurone (if sufficient neurotransmitters bind and threshold value surpassed)
26
What are the roles of synapses
Ensure impulses travel in only 1 direction 1 presynaptic neurone can signal to many postsynaptic neurones, this enables signals to be passed to different effectors Enable 1 sensory neurone to revive signals from several receptors, this provides information about extent of stimulus. Spatial summatation occurs- ie sometimes an action potential in a postsyanptic neurone will occur only if several presynaptic neurones release neurotransmitters Enable temporal summation- ie sometimes a postsynaptic action potential occurs only when several impulses have travelled down a presynaptic neurone. Each impulse releases more neurotransmitters until threshold depolarization is surpassed in postsynaptic neurone
27
What is the central nervous system (what types of neurones)
Brain and spinal cord Relay neurones
28
What is the peripheral nervous system (what type of neurones)
Everything other then brain and spinal chord Sensory and motor neurones
29
What is the somatic nervous system
Conscious control input from sense organs output to skeletal muscles
30
What is the autonomic nervous system
Subconscious control input from internal receptors output to smooth muscles and glands
31
What is the sympathetic and parasympathetic motor systems
Sympathetic: fight or flight responses, neurotransmitters-noradrenaline Parasympathetic: relaxing responses, neurotransmitter-acetylcholine
32
What is the function of the cerebrum where is it located
Coordinates voluntary responses Top of the brain (a bit right)
33
What is the function of the cerebellum where is it located
Controls balance and posture Weird looking tree bit bottom right of brain
34
What is the function of the medulla oblongata, where is it located
Autonomic functions (eg heart rate, breathing rate) Bottom of brain (just left of spinal chord)
35
What is the function of the hypothalamus, where is it located
Autonomic functions (eg thermoregulation) At the top of the medulla oblongata
36
What is the function of the pituitary gland where is it located
Release hormones that control other glands in the body Left of hypothalamus
37
Describe the stimulus, receptor, location of relay neurone, effector and importance of the knee-jerk reflex
Stimulus: firm tap below kneecap Receptor: stretch receptor in muscles Location: spinal chord Effector: muscles in upper leg Importance: maintaining balance
38
Describe the stimulus, receptor, location of relay neurone, effector and importance for the blinking reflex
Stimulus: touch on cornea Receptor: touch receptor in the cornea Location: lower brain stem Effector: muscles in eyelids Importance: preventing damage to the eyes
39
Describe skeletal muscle
Appearance:Striated Location:Attached to bones via tendons Type of contraction:Voluntary (conscious), fast, short in duration
40
Describe cardiac muscle
Appearance: striated (fainter striations then skeletal) Location: heart Type of contraction: involuntary, intermediate speed, intermediate duration
41
Describe smooth muscle
Appearance: non-striated Location: walls of blood vessels, digestive system, excretory system Type of contraction: involuntary, slow, can be long-lasting
42
describe the role of cell signalling in the nervous system (2 marks)
transmits nervous impulses between neurones across synapses/ synaptic clefts for coordinated responses to stimuli idea of summation
43
explain why homeostasis relies on cell signalling (2 marks)
receptor cells need to communicate with controller/coordinator/brain controller/coordinator/brain needs to communicate with effectors idea of several cell types/tissues/systems involved in responses
44
state the 2 structural differences between a sensory neurone and a motor neurone (2 marks)
position of cell body (described) sensory neurones has one (long) dendron motor neurones has many dendrites leading to its cell body
45
many relay neurones are not surrounded by myelin sheath, suggest why (2 marks)
relay neurones tend to be short the increased rate of conduction in the presence of myelin sheath would make little difference
46
explain why sensory receptors are considered to be transducers (1 mark)
they convert one form of energy to another form of energy
47
state the form of energy converted to electrical impulses by A: rod cells B: thermoreceptors C: Pacinian corpuscles D: olfactory cells
A: light B: heat/thermal C: mechanical pressure D: chemical
48
describe how the transmission of nerve impulses differs between myelinated and unmyelinated neurones (3 marks)
(with myelination) faster impulses saltatory conduction longer local circuits nodes of Ranvier present
49
explain why a neurone will not produce action potentials that vary in magnitude (3 marks)
all or nothing principle threshold potential must be surpassed no action potential will occur if Na+ ion influx is insufficient stimulus strength does not affect action potential magnitude (above threshold) K+ ion channels always open at the same point in an action potential (which results in the potential difference never surpassing a particular value)
50
describe how acetylcholine is released from a presynaptic neurone (3 marks)
calcium ion channels open/ calcium ions diffuse into presynaptic neurone vesicles fuse with the presynaptic membrane acetylcholine is released by exocytosis
51
use the concept of temporal summation to explain why a weak stimulus may be filtered out and not produce a response from the nervous system (3 marks)
a weak stimulus produces less frequent action potentials fewer neurotransmitter molecules are released less depolarisation (in post synaptic neurone) threshold is not reached no postsynaptic action potential
52
suggest why it is important for neurotransmitters such as acetylcholine to be recycled (2 marks)
to be released again from the presynaptic neurone regulates the concentration of neurotransmitter in the synaptic cleft prevents re-binding to receptors when signalling has stopped
53
which specific branch of the peripheral nervous system would produce the following responses A: a person gripping a cup with their hand B: an increase in sweat production C: constriction of pupils (3 marks)
A: somatic B: sympathetic C: parasympathetic
54
explain why a person struggling to move normally may have suffered damage to either their cerebrum or cerebellum (2 marks)
the cerebrum controls voluntary movements cerebellum coordinates balance and non-voluntary movements
55
state the location of the relay neurones in A: knee-jerk reflex B: the blinking reflex (2 marks)
A: spinal chord B: brain stem
56
describe and explain the general characteristics of reflex responses that aid the survival of organisms (4 marks)
few synapses short pathway a dangerous stimulus is responded to quickly innate/ no learning required the response is stereotyped/consistent/always the same involuntary prevents overloading of the brain
57
explain how the typical neural pathway of a reflex maximises its effectiveness (3 marks)
2 synapses short relay neurone sensory neurone does not need to travel deep into the brain responses is quicker
58
how will the length of the following sarcomere features change during muscle contraction (5 marks) A: A band B: I band C: myosin filaments D: actin filaments E: H zone
A: no change B: shortens C: no change D: no change E: shortens
59
outline the role of calcium ions in muscle contraction (3 marks)
calcium ions bind to troponin changes the shape of troponin displaces tropomyosin uncovers myosin binding sites on actin enables myosin heads to bind to actin

Biology Year 13 (12 decks)

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